1. Field of Invention
This invention relates to systems for controlling deformations in optical components. Specifically, the present invention relates to systems for controlling temperature related distortions of optical components in high power laser systems.
2. Description of the Related Art
High power laser systems are used in a variety of demanding applications ranging from target aiming systems to precision cutting devices. Such applications require systems with very precise optical components and accurate aiming capability.
High power laser systems typically include several optical components such as deformable mirrors and beam splitters. High energy laser beams often have uneven beam intensity profiles that result in uneven heating of laser system optical components. The uneven heating tends to distort optical components, changing the refractive and reflective properties of the components, decreasing laser system performance.
Typically, as the diameter of a laser beam decreases, beam irradiance increases. Increases in beam irradiance magnify distortions caused by uneven beam intensity profiles. Resulting component distortions often limit beneficial size reductions of high power laser systems and place costly design constraints on the systems.
Temperature related distortions are particularly problematic in the aperture sharing element of a laser system. The aperture sharing element is a beam sharing device that facilitates use of an optical system for both transmit and receive functions. Signals received through the aperture sharing element are used to aim the laser system. Uncompensated aperture sharing element distortions reduce the aiming and focusing capability of the laser system.
To reduce distortions of the aperture sharing element, high quality materials are typically used. The materials include low-absorption, optically efficient surface coatings, gratings, and aperture sharing element substrates. These materials are expensive and typically do not eliminate component deformations.
To correct any remaining aperture sharing element distortions, a variety of beam compensation systems are used. The systems typically include distortion sensing systems such as wavefront sensors, electronic control loops, and extra optical components to compensate for the distortions. Additional complicated circuitry and optical components such as deformable mirrors make these systems expensive and bulky.
These beam compensation systems typically include deformable mirrors. Deformable mirrors are placed in the beam path and selectively deformed to correct the beam for undesirable distortions. The mirrors include arrays of electromechanical actuators. Large physical spacings required for the actuators result in bulky deformable mirrors. Also, driving the actuators requires high voltages and expensive amplifiers. In addition, the mirrors cannot quickly control very small mirror movements. This limits the overall effectiveness of the deformable mirrors.
Wavefront sensors and deformable mirrors are typically used to sense and correct source laser optical distortions, beam train distortions, and atmospheric distortions. To correct for aperature sharing element distortions, additional wavefront sensors and deformable mirrors are typically required.
Hence, a need exists in the art for a cost-effective, space-efficient system for controlling deformations in optical components of high power laser systems. There is a further need for a system that can rapidly control small deformations in deformable mirrors.